His main point is that Common Lisp is better than Scheme when you need to get things done. Scheme may be more elegant, but it's not developed with a focus on practical utility (i.e. no sort function in the standard).
His point about the Lisp program being smaller is interesting, but still entirely anecdotal: we know nothing about the program, and for all we know, Greenspun was a Scheme novice at the time of the story.
I have a deep dislike for anecdotal "X vs. Y" stories because they don't shed any light on anything; they're just glib, cheap observations that make for a good story (albeit in this case, not that good).